Rotation #1: Association studies with candidate genes for non-syndromic cle palate. Malformations resulting in cleft lip with or without cleft palate are caused combination of environmental and genetic factors. Genes chosen were Osteopo Aspartylglucosaminidase and Retinoic Acid Receptor-alpha. Polymorphism dete unsuccessful in the Osteopontin and Aspartylglucosaminidase genes. For the receptor-alpha gene, seven pairs of oligonucleotide primers were synthesize different segments within the 3' untranslated region of the RAR-alpha gene. Reaction (PCR) was used to amplify DNA from 100 Philippines cleft subjects, controls, 20 Iowa controls and 20 Iowa cleft subjects. Amplified DNA was th SSCP gel to detect polymorphisms among these populations. A polymorphism wa among 15% of the Philippines cleft subjects but was not detected in any of t populations. Further research is needed to screen additional subjects from population and to characterize this polymorphism to determine whether it is with clefting. Rotation #2: Characterization of mutations in COLA1 gene of type I collagen with osteogenesis imperfecta type I. Osteogenesis imperfecta (OI) type I is the mildest form of inherited brittle bone disease. Fibroblasts from affected individuals produce about half the expected amount of structurally normal type I collagen as a result of decrea synthesis of pro`1, one of its constituent chains. Preliminary data indicat that OI type I results from mutations which affect the expression of COLA1, gene which encodes the pr alpha 1 chain of type I collagen. In this study, amplified genomic DNA from 25 affected individuals and 10 controls was scree by denaturing gradient gel electrophoresis for the presence of DNA mismatche Potential mutations were identified in two unrelated families. Amplified DN from each affected individual was cloned and sequenced to determine the natu of the DNA mismatch. Additional clones remain to be evaluated before defini characterization of the mutation can be made. Keywords: #1. Cleft Palate, Retinoic Acid Receptor-`; #2. Osteogenesis imp Collagen